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CAS NLB Failover Test

One of our Client has got CAS NLB with 2 exchange 2010 server in the same site.
The Databaseas have RPClientaccessServer pointing to the CASArray.
All the exchange server are 2010 SP2 rollup 3.
When one of the the CAS server goes down, they need to restart the outlook to connect back again. Is this the normal behaviour with CAS NLB or where can start looking for this issue.
All the servers are on Virtual (vmware) and CAS NLB is using multicast
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Malli Boppe
Asked:
Malli Boppe
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1 Solution
 
Exchange_GeekCommented:
Here is the reason why

A CAS array object performs no load balancing. It's an Active Directory object used to automate some functions within Exchange and that's all. Exchange 2010 documentation says all over the place that it's recommended to use load balancers (LB) to load balance CAS traffic

Ref: link

Precisely, it is a problem with you're LB and not CAS.

Regards,
Exchange_Geek
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Malli BoppeAuthor Commented:
Thats true bu we have CASArray pointing the windows NLB
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Exchange_GeekCommented:
You're working against MS Recommendations

http://www.stevieg.org/2010/11/exchange-team-no-longer-recommend-windows-nlb-for-client-access-server-load-balancing/

Read the link carefully to understand WHY MS doesn't recommend it.

Regards,
Exchange_Geek
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Malli BoppeAuthor Commented:
Yeh understand that it not recommended  by MS in a enterpsie setup. But  definately in a small exchange organisations its definately supported.

WNLB can be the right fit for organizations that do not have:
 More than 8 nodes in a WNLB based array (the Exchange Product group does not recommend more than 8 nodes in a WNLB based cluster due to scalability and functionality limitations).
 
Requirements for the LB solution to be application-aware (check state of application and not just check for IP connectivity like WNLB does).
 
The need for affinity methods other than source IP address based affinity which is the only method provided by WNLB (a HLB solution provides other affinity methods such as cookie and SSL ID based affinity).

http://www.msexchange.org/articles_tutorials/exchange-server-2010/high-availability-recovery/load-balancing-exchange-2010-client-access-servers-using-hardware-load-balancer-solution-part1.html
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Exchange_GeekCommented:
If you still want to continue working on it, try checking which box is responding OR which box is OL connecting to using netstat -a

Regards,
Exchange_Geek
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Malli BoppeAuthor Commented:
This is an expected behavior so nothing much can be done.
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Malli BoppeAuthor Commented:
Got a  response from ms forums saying that its an expected behaviour
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